Knuckle: Ring Sizer

Lay a ring you own flat on the screen, match the circle to the band, and read the size. No camera. No jeweler.

Knuckle turns your screen into a ring sizer.

Lay a ring you already own flat on the display, match the gold circle to the inside of the band, and read the size. That is the whole thing. No camera, no printing, no paper strips to cut out, no trip to a jeweler.

Before the first measurement you line a bank or ID card up against an outline, once, so Knuckle learns exactly how large a millimetre is on your particular screen. Every reading after that is true to your device.

You get the inner diameter in millimetres next to the sizes people actually ask for - US, UK, EU, Japan, Australia, Hong Kong and Italy. Each result carries an honest confidence band instead of one number pretending to be certain.

Sizes are worth keeping. Save one under the person it belongs to, note the finger and the hand, and look it up later while you are standing in the shop. Send a clean size card to whoever is buying.

Nothing leaves your device. No account, no sign in, and it all works with the network switched off.

Privacy Policy: https://docs.google.com/document/d/e/2PACX-1vTDX9pxPOlUJl_skVUHPi99mAw0y2B2BYd_v1mJkoF3xW3rlOcW5KlYd4t93MMbbGhctSTnBTy7d_l6/pub

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/